7: Week 7: Soil Insects - Biology
Soil structure is important for bed formation. Beds are made five feet apart, center to center.
Soil pH. Optimal strawberry production requires a favorable root environment and the availability of essential nutrients. Soil pH is a key factor in maintaining a favorable root environment. Soils with a pH between 6.0 to 6.2 promote the best growth. A soil test can indicate what amendments need to be added to correct the pH. Soil testing services are available from NCDA&CS regional agronomists.
Low pH is one of the most frequent problems identified on soil samples. Because the problem cannot be corrected after planting and low calcium (Ca) usually accompanies a low soil pH, testing and liming the soil as needed is especially important. Incorporate the lime based on the soil test recommendation at least two months before transplanting.
Soil moisture. Strawberry plants require a continuous supply of water during periods of active growth, and drip irrigation is the most efficient method for slowly applying small amounts of water directly to the strawberry plant’ s root zone in the pre-bloom, bloom and harvest period. It is important for growers to keep in mind that a standard 8- to 10-inch strawberry plasticulture bed has very poor capillary water movement and a drip irrigation system is going to be required to meet most of the moisture requirements of the crop. But, with good management of a drip irrigation system, strawberry root zone moisture content can be maintained close to optimum for plant growth, or near what is called “field capacity.”
In North Carolina, it is common practice to use the drip system to establish plug transplants in the late summer, but some overhead sprinkler irrigation should still be applied for the first two to three days after transplanting. It is also recommended that growers hook up their drip systems soon after planting for a post-plant chemical injection of Ridomil Gold if transplants are suspected to be infected with crown rot (Phytophthora cactorumi), or when a field has a history of this disease. To aid transplant establishment in October and November, it may be necessary to run the drip system for a few hours every few days during weeks of little or no rainfall. Drip systems are “winterized” in the late fall and are not re-connected until early March (around the time of new leaf development). Water loss from plants is much less during the dormant season (December to early February), and winter rains generally furnish adequate soil moisture through early March. However, in warm periods during mid-March (pre-bloom) it is not unusual for the crop’s water requirement to approach 1 inch/acre/week. On a daily basis this is about 3,880 gallons (1 acre-inch of water = 27,154 gallons). During the bloom, fruit set and harvest period, crop water usage will climb to 1.5 inches/acre/week (0.2 inches/acre/day), and in warm/hot weather it becomes necessary to apply as much as 1.75 inches/acre/week (0.25 inch/acre/day).
Soil erosion and surface water management. Although raised beds encourage water drainage within the soil, plasticulture growers frequently encounter problems with getting rid of excess surface water. Because 50 percent of a plasticulture strawberry field is covered with an impermeable plastic film, the field should have enough slope that surface water drains uniformly and gently from the field after periods of heavy precipitation without causing erosion or leaving puddles. On fields with more than a two percent slope (a two-foot drop over 100 feet), continuous overhead sprinkling for establishment of fresh dug plants may cause severe soil erosion. It is often a good idea to broadcast annual ryegrass at a rate of approximately 50 pounds per acre over the entire field the same day you finish fumigating (before planting holes are punched). Ryegrass will reduce soil washing in the aisles after heavy rains or establishment irrigation on sloping terrain. The ryegrass should be killed or stunted by an application of post-emergence grass herbicide when it is about six inches tall or prior to applying the winter row cover.
Seedcorn Maggots Get an Early Start
Seedcorn maggot is a seed and seedling pest of corn and soybean. The larvae, or maggots, feed on germinating corn and soybean seeds or seedlings (Photo 1). Feeding can delay development or kill the plant. Plant injury is especially prevalent during cool and wet springs when plants are growing slowly. Infestations tend to be field-wide instead of in patches like for many other pests. To confirm seedcorn maggot injury, check field areas with stand loss and look for maggots, pupae and damaged seeds (hollowed out seeds or poorly developing seedlings).
Photo 1. Seedcorn maggot on soybean. Photo by University of Minnesota Extension.
Seedcorn maggots overwinter in Iowa as pupae in the soil. Adult flies emerge and mate in April and May, then females lay eggs in soil. Once the eggs hatch, maggots feed for 2 to 3 weeks before pupating in the soil, where they remain for 7 to 14 days before emerging as adults. The entire life cycle can take as little as 21 days to complete, resulting in 4-5 generations per year in Iowa Maggot densities are higher in soils with high organic matter. Land that is heavily manured and soil that has been recently tilled, regardless of residue type, is attractive to egg-laying females.
This fly species has a lower developmental threshold of 39°F and upper threshold of 84°F. Peak adult emergence for the first generation occurs at 360 accumulated degree days since January 1. Based on current accumulated degree days, the first generation of adult seedcorn maggot has likely emerged throughout most of Iowa (Figure 1). Forecasted cooler temperatures may slow development.
Figure 1. Accumulated growing degree days (base 39°F) in Iowa from January 1 – April 8, 2021. Map courtesy of Iowa Environmental Mesonet, ISU Department of Agronomy.
Seedcorn maggots are white or pale, legless and 1/4 inches long with a tapered body (Photo 1). The maggots have a black mouth with hook-like mouthparts to feed. The pupa is brown and looks like a “wheat seed” (Photo 2). The adult fly is grey to brown in color with red eyes. Adult seedcorn maggots are 1/5 inches long and look like a small house fly (Photo 3).
Photo 2. Seedcorn maggot (left) and pupa. Photo by Brian Lang.
Photo 3. Seedcorn maggot adult. Photo by www.ipmimages.org.
Corn and soybean seeds injured by seedcorn maggot larvae can show a range of symptoms. The most obvious is reduced stand or gaps in the row. This happens when maggots burrow into the seed and consume the embryo, preventing germination. Even if plants germinate, seedlings are typically weak and may die. Any condition that delays germination or causes slow plant growth may also increase damage from seedcorn maggot.
There are no rescue treatments for seedcorn maggot. No-till fields are less attractive to egg-laying females. Target planting when soil and moisture conditions are conducive to quick germination and vigorous growth to reduce seed and seedling pest problems. Farmers with persistent seedcorn maggot infestations should consider a later planting date, shallower planting, higher seeding rates, and earlier termination of cover crops (Bessin 2004). Waiting two weeks (or 450 growing degree days) after tillage or manure applications to plant corn or soybean should provide enough time for the seedcorn maggots to complete development and move to another host (Gessell and Calvin 2000).
Insecticidal seed treatments can adequately manage seedcorn maggot, unless there are high densities of maggots. If an insecticidal seed treatment is not used, tracking GDD and modifying planting date is the best option. If significant stand loss occurs, replanting the field is an option. A replant decision should be based on percent stand loss and cost of additional seed. Resources for replant decisions are available:
Bessin, R. 2003. Seedcorn maggots. ENTFACT 309, University of Kentucky Cooperative Extension Service.
Gesell, S., and D. Calvin. 2000. Seed corn maggot as a pest of field corn. Entomological notes, Department of Entomology, Penn State University.
Holm, K. and E. Cullen. 2012. Insect IPM in organic field crops: seedcorn maggot. A3972-01. University of Wisconsin Extension.
Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Integrated Crop Management News, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on April 12, 2021. The information contained within may not be the most current and accurate depending on when it is accessed.
Biology of sawflies
Most sawflies in Minnesota have one generation per year (that is it takes one year to go completely through their life cycle once), although some go through two generations.
Adult females use their saw-like ovipositors to cut slits into needles, leaves, or tender new shoots to lay eggs.
Eggs hatch into larvae that feed on foliage of their host plants for about four to six weeks.
- It is common for most sawflies to feed gregariously, in non-social groups.
- When in such a group, if they are threatened, they can simultaneously raise and arch their bodies as a defensive tactic (presumably to scare away would be predators).
Many sawflies overwinter in the soil as pre-pupae (the stage between a mature larva and pupa) or pupae in cocoons some species also overwinter as eggs or larvae. Adults typically emerge in the spring or early summer.
When sawflies are first active in the spring depends on:
- Where in Minnesota they are found (generally the further north in the state, the later they will first become active).
- Whether spring is early, late, or normal.
7: Week 7: Soil Insects - Biology
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Introduction To Plant Production
Next course starts: 03 August 2021
Length: 7 weeks
Part time: 10 hours per week
Price: R 4,400
The AGRICOLLEGES international Introduction to Plant Production short course is a 7-week programme designed to introduce students to the world of plants and, more specifically, crops in the agricultural sector.
This course is ideal for emerging farmers, recent school leavers or even established farmers wishing to upskill themselves or refresh their basic knowledge of plant production to be applied in a wide range of agricultural practices.
During the 7-week period, students will receive a comprehensive overview of plant biology, ecological concepts, soils and pests. After completion of this level students will be better equipped to work in a plant production environment.
After completing this course, students will be:
- Able to understand the basic principles that apply to plant production
- Able to identify concepts relating to ecology, soils, plant biology, insects, micro-organisms and pest management
- Able to demonstrate a sound understanding of the basics of plant production as a generic concept
- Able to articulate the importance of specific plant production practices and apply these
Or contact us for more information
- The course is open to anyone, from anywhere in the world.
- There are no formal entry requirements, although prospective learners will be required to complete our admissions assessment to ensure basic proficiency in the English language, numeracy and computer literacy.
Note: All learning takes place online and students will require regular internet access via PC, tablet or phone to successfully complete this course
The course will start with 1 (one) week of free self-study in a preparatory orientation course including:
Students will receive a certificate on completion of the orientation course.
Once preparatory courses have been completed, learners will work through 6 (six) core modules:
- Ecological Concepts (including Climate)
- Plant Biology
- Insects and Nematodes
- Micro-organisms (bacteria, viruses and fungi)
- Integrated Pest Management
AGRICOLLEGES international’s online short courses combine e-learning with practical and shared learning opportunities in a three-pronged approach:
- Students learn independently through the online tool
- Students and lecturers collaborate online to share information and learn from each other
- Students do remote practical assignments at home, filming and recording their work with a mobile device and uploading the photos or video as evidence on the Learning Management System (LMS).
Our Learner Management System (LMS) includes advanced tools and functionality to enable a full suite of blended learning opportunities. The Desire2Learn (D2L) Brightspace LMS delivers this functionality through its South African based distributor and partner, Visions Consulting. Brightspace is a digital learning platform that helps schools and institutions deliver powerful, secure and personalised learning experiences.
Each group of students is allocated a Course Consultant who oversees the progress of students. Regular communication, notices and guidance is offered by the course consultant. Students are encouraged to also communicate with each other and share their course experiences. This allows for a deeper and more meaningful learning experience.
What is the Life Cycle of the Cat Flea In Indiana?
The life cycle presented here is based on the cat flea, which has been studied extensively. Like all fleas, the cat flea develops from egg to adult via a process of "complete metamorphosis." This process involves the transformation of the last larval stage into a non-feeding pupal stage. Adult males and females live nearly all their lives on a host, and blood sucked from the host is their only food.
Females require blood for the development of eggs, and continue to lay eggs as long as they take blood meals. They are capable of laying 25-40 eggs per day and have the potential to produce about 2,000 eggs in their lifetime. Eggs are laid on a pet, but are not glued to pet hairs. They resemble tiny oval pearls, are relatively heavy, and quickly fall off or are shaken off by the pet. Eggs hatch within 2-5 days under suitable conditions of warm temperature and relatively high humidity. Cat fleas have three larval stages, none of which live or feed on a host.
The three larval stages can be completed in 7-14 days under suitable conditions of temperature, humidity, and availability of food. Cat flea larvae feed on organic matter in or near the resting or sleeping site of an infested pet. They can survive inside dwellings for a few weeks without feeding, but require food before molting into a pupa. Cat flea pupae usually develop into adults in about 1-2 weeks, but can survive for several months inside a dwelling (or outdoors in warm weather) and quickly emerge into adults when stimulated by vibrations produced by an approaching pet or person. Adult cat fleas can survive for weeks indoors without feeding, but egg development does not occur in unfed females. The entire life cycle of cat fleas usually is completed in 21-28 days, and several generations can occur each season, but reproduction typically does not occur during winter in Indiana.
Bugs 101: Insect-Human Interactions
Of all the animals on earth, which are the strongest for their size? What about the fastest? Who were the first animals to evolve flight? Insects take all of these titles and more! As the most abundant animals on the planet, insects and other arthropods affect our lives in so many ways. From beneficial interactions like pollination and biological pest control, to the transmission of life threatening diseases this course will teach you about the big ways that these little arthropods impact our lives.
In Bugs 101: Insect-Human Interactions, you will be plunged into the diverse (and sometimes alien) world of arthropods to learn how they work, what they do, and how insects and humans interact every day. After completing this course, you will be able to: Describe the evolutionary relationships between insects and their arthropod relatives Inventory major groups of insects and their diversity Demonstrate evolutionary adaptations that make insects successful Discuss insect biology and human-insect interactions Evaluate positive and negative interactions between insects and humans Propose practical and symbolic roles insects play in human societies
- All buds
- Close up
I’m going to harvest these plants today. They use little water and the leaves are starting to turn yellow. About 70% of the hairs are brown, which I think is exactly right for a white widow. Move on to the next section to see how you should harvest, dry and trim the plants. But first, check out this photo series on the development of the buds. Good luck harvesting.
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